I got a pair of size 12 Terrocs over the weekend and I'm wondering if I shouldn't have gone for an 11.5? From what I've read doing a quick search here Terrocs should be quite a 'close' fit and whilst the 11 felt too close the 12 is possilby a little lose, especially allowing for stretch? 

The assistant in Cotswold was friendly enough, but didn't seem to be 100% accurate on his footwear as he told me that Terrocs aren't very good for walking!! With this in mind I doubt he would have been able to go into the finer details of sizing/measurements.

I have to walk past Snow and Rock's Monument store on my way to the station, or with a slight detour I can go to their Covent Garden branch. Does anyone have any experience of the Monument store, do they do a good measuring/fitting service? Or am I better heading to Covent Garden?

Haven't used the Monument branch of S&R but the Holborn one (Grays Inn Rd) had a good footwear specialist when I was last in. The guys in Covent Garden helpful too.

When I tried to buy some in Cotswold the assistant swore to me that inov8 didn't do half sizes. I assured him, they do - it's just that you guys don't stock them!!

The 330s do stretch a bit and if they're loose already could cause problems like blisters down the line.

Try 11.5s - walk up and down the slopey rock thing a few times to see if you feel yourself slipping into the toes coming down or feel any heel lift going up and have a good walk around the shop. I always go up and down the stairs a few times too. Make sure they give you enough time and space to feel certain you've got the right ones for you.