I was waiting for you to ask more and when you did not I thought I would just elaborate.
Without a picture or radiographs it is difficult for me to answer completely. You said your dentist did not refer you to get a deep clean or talk about splinting. To me, that suggests that she deems the teeth unable to be saved. If you wanted to send me pictures or radiographs I could confirm her diagnosis if you like. As for not discussing why the bone is lost, I don't know why. Dentists at the NSH can be rushed and low paid and will sometimes neglect these explanations as they are time consuming.
Put simply, the bone loss could have occurred due to your grinding , periodontal
disease, poor hygiene or all of the above.
Getting implants is expensive and demands rigorous hygiene care so you don't lose them too.
You have a difficult decision to make. Saving for or using credit are options. You may even get the denture and then start to save for them . They can be placed later.
Best to get the problem teeth addressed as well as you can afford and plan for your implants later.
Let me know if you need more help or want to send pictures or x-rays.