> I purchase my own software licences and claim it on tax

In theory you could do this via the UK tax system too – there’s a field on the Self Assessment forms that allows you to claim work related expenses that weren't reimbursed by your employer

One of my past employers paid a reduced mileage rate so I used to claim the difference on my tax return.

Quite how it would work for software I’m not sure though i.e. what’s the test for a permissible expense