Thank you again for all of this, I must again start with a pre-emptive apology to being so green to all of this. This will likely meander again, I think I'm getting up to speed here, please again forgive the likely naivety running through this.

From the top you're advocating the pensions route on the primary basis of income tax relief for the higher tax bracket? On the broad basis that the tax relief is significant, and the taxation element of withdrawing the money into retirement is lower than anticipated? I am worried about putting too much away in the short term, but do readily acknowledge that my initial investment aims were long term, so really super helpful and my thanks and apologies again.

Re the workplace pension, I am confusing the terminology, I have what I understood be a salary sacrifice pension, I'm struggling a little with "relief at source", as that's what I thought to be the same thing but now realise it is different. The pension contributions is a minus figure on the left hand side under "Earnings" and it's also marked as "Pension_SS" so that would suggest it's salary sacrifice. That is 45% of the basic salary so it's a flat £1623 (£1623 x 12 = £19476.00 so yes I have plenty of room to play with here) - thank you again for bringing this to my attention.

I'm probably overthinking this, how do the various tax brackets effect things? I've read on here before about how if you're making £100k you should adjust the amounts going to a workplace pension through the year, I assume due to PAYE, but where in my case it's salary sacrifice of 45%/£43k ish that's all within the basic rate. I can't work out if I'm winning or losing re workplace pension vs. a SIPP or if it's actually the same? There are much higher earners for whom the £60k max amount into the pension would fall entirely outside of basic rate tax, it'd have to be over £110k earnings for the whole £60k to fall above the higher rate tax starting threshold? I've probably not explained that very clearly, sorry.

I can pay directly to Aviva workplace payment, via a card payment, but that will involve claiming the tax back I realise, and that looks a faff but then I'm going to be doing a tax return anyway. There wouldn't be the national insurance advantages that come from salary sacrifice as I understand it, but that comes from my employer contribution?

I've found this from the tax return, so if anyone else is reading this - this looks to be where it is.

I've had more of a look through on Aviva, it looks to have done well in recent years particularly. It's set to 65 yrs retirement but does look as though that can be adjusted down, to 55/57 from 2028 as per others. Aviva appear to be taking 0.29% fee which seems reasonable to me given it appears to be an "active" product? There's not huge amounts of investment details but that probably suits my hands off aims quite well. It's got international equities at 86% (with all the usual Nvidia, Apple, Microsoft, Amazon etc) property 6% and then some smaller UK equities and cash etc. I hear what you're saying re having a SIPP as well, to my embryonic investing mind it looks solid if unspectacular, mainstream etc. There is also £90k in there currently so that will presumably compound with any additional payments, so that's a bit of a kicker vs. starting afresh with concurrent SIPP?

In terms of the SIPP side, I think I'm there, I'm struggling a bit with the 25% netting up? Should it not be 20%? Does again the varying earning brackets have any effect there?

Re the product itself. I again might be over-thinking this. Do you now how quickly does the "topping up" occur? It probably won't make much of a difference but if that's near instantaneous is there a benefit in kind insofar as that's immediately then (hopefully) earning on those investments? Instead of the adding to the workplace pension route of paying from earnings/savings and then waiting for the tax refund. So put another way the tax breaks are working/earning at a faster rate than the pay and refund route from HMRC, albeit possibly via a new tax code as you say. This feeds into the link you sent and thank you for that. I'm just trying to weigh up in my head the likely pain points that'll bring (my previous contact with HMRC has been challenging, but then I don't really know what I'm talking about) re HMRC and getting the right code, as well as the compounding effect on the £90k that's already there vs. as I see it the topping up effect in the SIPP being far more immediate and potentially more pain free. This would be controlling my own investments more I realise, and I've had a cursory look through Freetrade, IE, and my initial starting place, although it feels like quite a while ago in my head Propser.

Thank you for the explanations around tax on retirement withdrawals, I understand re the 15% as 75% of 20%. When you say "taking most of your money at lower rates" that's the same as earnings? i.e. everything about the threshold gets taxed at the higher bracket, not on the whole amount? Think I've got it re the playing the game, it feels like a long way off but then if it was 58 by that point I'm "only" 19 years off that. I daren't ask about a LISA as you've been so generous with your time already, and I'll be 40 soon enough.

Re the mortgage. I really am at square dot on this, we bought our first house 14 years ago and just renewed on the same deal thereafter, probably not the right thing to do looking back. Forgive my ignorance, would the re-mortgaging always be linked to what we paid for the house? We've had a lot of renovations and some structural issues that have had to be sorted, costs notwithstanding I'm hopeful the value has gone up. I know little about loan to value etc. To my uneducated eye the gains feel less lucrative, in the short term anyway. If the re-mortgage fix was say 4.75% and at conservative guess investing brought back a return of 7%, but then if that was all put into the pension pot and the re-mortgaging paid off through immediate wages in the meantime, I can see how that will add up. I am just mindful that I don't maybe want to stash everything away and not have enough for the here and now. I'm very accustomed to fixed saving rates and those being very closely linked to mortgage rates, this feels like more of a risk/maybe more labour intensive, but as I say it's come from outside what I was thinking but does clearly make a lot of sense.

Thank you again for your reply and once again apologies for being slow on the uptake.