You do not need a solicitor to apply for divorce. You can actually call into the local county court and pick up the forms, fill them in and return them. There is a fee but you may be able to get that waived if you are on certain benefits or a low income. I don't know the rules but it has to be worth asking.
As for a contested divorce, years ago I worked in the county court and I worked there for over a decade. I never, ever saw a successfully contested divorce. If your stbx takes legal advice then a solicitor will tell him it will cost him a fortune and will be unsuccessful. If someone doesn't want to be married then nothing can keep them there. If your stbx does contest it, he will have to pay all the legal fees and court fees. Always, always, always ask for him to pay your costs at any hearing.
I suggest that you go over to the legal board on here and check about grounds. You will certainly need to get advice for the financials but for the first bits you can scrape by. The only thing you may like to get checked by someone is the grounds for divorce. If he is determined to spend a fortune contesting the divorce then they are going to be the target.
Another route you may like to take is to go for a legal separation. I don't know much on that, but if you can prove you have been separated for five years then your stbx will have no grounds at all to contest a divorce.
I hope that is helpful. What I also suggest is that you keep repeating to yourself, 'it doesn't matter what he thinks, it doesn't matter what he thinks, it doesn't matter what he thinks..' because it doesn't. tbh you could change the locks, refuse to admit him without a court order and refuse to allow access without a court order. Whether you feel strong enough to do that is another matter. Good luck.