Good schools are like gold dust. I wouldn't necessarily be adverse to moving to a different "good" school - and I know lots of people have no choice but to do this - but where there is an element of choice involved there'd have to be a damn good reason for me to move my kids otherwise.
When I was previously a single mum, I found myself in the position of having to move as I could no longer afford to stay where I was and unfortunately therefore took myself out of catchment for a "good" school my oldest would have otherwise attended (and we moved a fair bit less than 20 miles). The alternative was okay but not as good results wise, and there was also the effect of my child having to make new friends etc. It wasn't the end of the world, but I do think it set them back for a while - and I would have preferred not to have had to put them through that .... though believe me I tried every which way and the numbers simply didn't add up.
In your situation, no way would I take my kids out of schools they were thriving in if there wasn't a sound reason - and indulging someone else's hobby is NOT it. In fact it's ridiculously selfish ...... many of us would happily drive 20 miles (or more) to do a hobby so you can only conclude that if he wants it right on the doorstep he'll almost certainly be grabbing every opportunity to do said hobby and you'll be left on your own perhaps more often than you'd like to be anyway. If things didn't work out re: schools, imagine how bad you'd feel for having moved just so he can go out to play whenever he wants!
Like everyone else has also said, I personally think 10 months is far too soon - not to be thinking of moving in together necessarily - but for him to be laying down the law about where you live. Scrap that, he shouldn't be laying down the law no matter how long you'd been seeing each other actually .... but it does strike me as very off that he feels his wants as opposed to the children's needs (and good education is arguably a need) take priority. I think that's a red flag TBH - would wonder how else he might throw his weight around in future as he obviously considers himself Mr Important.
... and I say all this as a stepparent whose life has been significantly affected by other people's choices, which yes, can be extremely frustrating and unfair (in our case, we are dealing with a very unreasonable ex) but I don't see why, in your case, if he really wants to be with you, he'd be disgruntled or disrupted at moving into your area when he's not tied elsewhere due to work issues, or because he also has kids and when his hobby would take 30 mins to get to. Call me cynical but makes me wonder if he's always had this pipe dream of living by the coast but couldn't afford to do so without someone else's input ? In other words, you're a means to an end (sorry to say). Otherwise, if living there is so important to him, why hasn't he already moved there ?