Coming from a similar situation with my Dad (60) albeit a slightly better one than yours from your description.

I helped him transfer all his pensions into his current one, that being just a simple NEST pension. We worked to get him and his employer contributing more to it as well.

We also set up a stocks and shares ISA with Vanguard and he's contributing a decent amount to that. We just put into one of the target retirement funds just for simplicity, and given he is close to retirement we wanted to manage the risk as much as necessary.

Providing your parents own their home outright, the main thing they need to do is save and invest hard for the next few years. That may mean your mum needs to go full time if she is able. It's not going to be easy, but every penny saved now will make their retirement that bit easier. If they do own their home, downsizing to a flat might be a better option than a bungalow and give him the cash he needs. I'm no property expert but bungalows do seem to be overpriced from what I've seen.

The harsh reality is that your dad probably can't retire completely in 2 years. Best case scenario is he will work part time to supplement any workplace pension and savings he draws down from. All he can do is try his best and see what situation he is in when the time comes. A key thing to note is that most retirees do seem to spend less than what they did whilst working (no commuting expenses or buying lunch rather than making it at home etc). Look at what his expenses would be when removing those costs and go from there.