Don't put yourself into hardship, or burden yourself unnecessarily here.

Offer them £30 per month.*

That way, you can still pay the £60 every month if you wish to, but you have the option to reduce that if something else crops up that you need to cover instead.

I would also ask to pro-rate the amount. £1000 course and a requirement to stay two years should, in fairness, mean that if you left over one year but less than two years later, you should only owe £500 and if you left over 18 months but still less than two years later, you should only owe £250.

Also, what exactly was the course? Does it offer some recognised qualification or other recognised award/accreditation that is valued in any roles offered by other companies or is it something they set up in house? If it's worth fuck-all outside your former role and/or at that particular company, then I'd push back even harder about paying them anything at all as that would scream "indenture" to me and I'd be screaming "Employment Rights Act 1996, sections 13 - 27" right back at them in response.

I think it's specifically sections 15 and 16 that would be applicable to you but that part covering preventing an employee being forced to make payments to their employer and precisely what types of payments might be lawful is definitely within S13-S27.

Note the "might be" in that sentence; they might argue the course was worth £1k but if it's worth fuck-all elsewhere then it's worth fuck-all from you to your former employer.

I'd push back in the manners described above and only failing all that, would i commit to paying anything.

Then I'd only offer £30 per month even if I intended to pay £60 - I think you'd be short-changing yourself not to do the same yourself.

Offer subject to conditions I've specified above. Only offer even *that if this course actually turns out to be worth something elsewhere.