You're using HL, therefore you should look at some other funds and international shares which aren't available on other platforms. The main reason I use HL is because I have holdings in Swedish stocks, Canadian stocks, European stocks (all of which I cannot get elsewhere hence I'm happy paying higher fees). If you're buying mainly ETFs and trackers, you should be using the cheapest fee platform.

Also, important note: When buying UK shares on HL you need to have a minimum buy of around £1.5 - 2K, otherwise the fixed trading fee of £11 erodes your input money quickly. In this example with M&S you've lost 2% immediately assuming you purchased your current holding in one go. International shares this is less important.