When I bought mine OTR were by far and away the cheapest, but that was down to a favourable exchange rate. Brexit has firmly closed that door though!
To be honest, Ohlins stuff is 'price-fixed' - they don't allow dealers to discount. You'll find that wherever you go, they will be around �120. Factors like shipping costs will probably be the only difference.
Might be worth just going and visiting your local suspension shop/Ohlins dealer to see what they can do. Even if they're still �120, at least you might score a mug of tea and some banter, as well as get a nice rideout to boot!
Your nearest Ohlins dealer (Aurok Engineering) is a short blast over the South Downs in Alton.
https://www.facebook.com/pg/AurokEngineeringLtd/about/