So very sorry to hear about your DH, I do hope you are taking care of yourself during this awful time.
Finances are such a worry, but my first bit of advice would be not to react too quickly, I had a knee jerk reaction when I was left alone to deal with the money, got rid of my car, downgraded my TV packages, went onto comparison sites about the best deals for household and insurance expenses, all done in a rush. I wish I had been less frantic and calmer.
Secondly, check out your insurances. I did not know that when my husband was declared terminally ill, one of his insurances would have paid off the mortgage for us, which would have taken such a worry from his mind in his last days.
After four years I sold our house and down-sized, but the house took a lot of my profit to bring it up to a decent standard, but thinking ahead, the price will have gone up substantially because of the work I had done. In retrospect I sometimes think I should have moved into a flat, without a large garden to care for, and with more money in the bank, but I love this house and it is all mine, with no memories of the place where DH died, and that has helped me enormously.
We had private insurances, which as a self-employed person with feast and famine days, I often worried if we could afford the payments, but my husband in his wisdom insisted we keep them.
I get an increased National Insurance Pension, plus monthly payments from my DH's private ones, which I must add are taxed at source, so theoretically you should not have to worry about tax returns and the like, unless you receive any other payments. Sale of personal stuff does not get counted into this. My Pensions end in another two years, at which time they go to 50% of the amount at the moment. I am getting stuff down around the house and in the garden anticipating when this decrease happens, while at the same time saving what I can in PEP's which are tax free on interest, and in a savings account for that rainy day.
I still worry about money and have to remember that DH is no longer working to top up any amount of money I get, but I am forever grateful that he insisted on paying the private pensions, even during lean times, because without that I would definitely be struggling.
I think you have more than enough to worry about as your DH's days come to an end, so if you can, get an independent financial manager to discuss things with you for the future. Make your own Will asap after DH passes away, but please, please do not make your bank or a solicitor your Executor. I have known so many people who do this and it costs them a small fortune Gross and before tax and other bequests, often leaving them with a small percentage of their inheritance.
This sounds so formal and I do not with it to be at such a heartbreaking time, obviously your mind is racing ahead, but for me, time enough to worry about things after the dreadful time. I hope when the end does come it is peaceful and you have time to yourself to grieve.