If you own the phone I would look at Giff gaff (O2 as carrier) you can get a rolling monthly contract at, say £10 pm for 500 mins, unlimited texts and 1 gig downloads with 4 G . The phone needs to be unlocked or linked to O2. No way would I sign a 24 month contract! Bought my used I phone 5s for £170.
Surface Pro (2017) vs Surface Pro 4