All the exchanges that do have GBP go via a European bank and you get hit for international wire fees and withdrawal fees that make it not worthwhile for £114.
On cex.io the withdrawal fees for GBP are at 1% (
https://cex.io/fee-schedule#/tab/payments) which is fine, i'd say. Thats 1,14 £.
There are definitely exchanges with a lower fee (e.g. kraken with just a few cents in ) but for occasional purchases this is quite ok.
IMO using an exchange is safer (and sometimes also cheaper) than using localbitcoins.