Our house is bought but under his name. However I have been about £20,000 into work on the house which you can see from my bank statements. Does this mean when he sells the house I get some of it?
Short answer is yes, most likely but you need to check and pronto.
I was in exactly the same boat as you - not married and house in ex's name. 10 year relationship also.
Because you are unmarried, you don't have much in the way of legal rights (as I know to my cost) but if you can prove that you have directly contributed to the increase in value of a property during the relationship, financially or through work, or other means - then yes, you have a case in terms of getting a share of that increased equity, especially if you have proof of payments and a clear paper trail.
I had sold my (single) home and the proceeds had gone into doing up his house (what became the family home) and investing in our joint business. I was advised I had a good case, but decided not to fight in the end because 1. it would have kept me in long protracted 'contact' (albeit not necessary face to face) with the bastard (who I knew would make it as difficult as possible) and 2. it had taken me that long to get away from him, I decided that my freedom was worth more than the few thousand quid I might get from any 'settlement' particularly after legal fees were paid etc. So I cut my losses.
Doesn't mean that you should though. Get legal advice as soon as you can.