@Neil *******
you're only wanting to stay here 90 days so a Single Entry Tourist visa is plenty at £30 versus £150 for the 6 month METV. So unless you're gonna be here to use a METV don't waste the time or money applying for it
Now on the other hand (as James pointed out) IF you're wanting to stay up to 9 months in 60 day increments the METV is a choice as the STV is discontinued
AND
the METV can be gotten online from the thai consulate in the UK by selecting tourism and leisure activities, then multiple entry