My driving licence is about to expire, I read time ago how to exchange it with a UK driving licence, is the process different for the renewal instead?
If you are a resident in the UK, then you won't be able to renew your Italian licence and keep it as Italian, you have to exchange it to a UK one. This is global to all EU countries:
If you move to another EU country and the validity of your EU driving licence expires, you will have to renew your licence in the country where you are normally resident
When you exchange the licence they will actually send you a new one, with the original categories from your old licence, but with a new validity date. In the UK this is usually for 10 years, unless you are nearing 70 years old.