Hi Ohtwo,
This is a recurring them and I have posted on some previous threads, suggest to do a search on VAT and I am sure it will show up.
Just to be sure, you need to accrue a liability of 21.5% over the price you pay your UK supplier (who charges you zero VAT rate), but you are also entitled to claim a deductible for the same amount.
Now, there is a body of opinon that suggests because the effect is VAT neutral, not to bother adding the liability in T1 and claim the corresponding deductible in T2 on your VAT return. However, if you read the notes on your VAT3 return it clearly asks you for those figures, so in my view, it should be included.
You're on the right track in any event and would hope that the answers in this thread have answered your question
best regards,
Rudolf289