James Miller from what he wrote in his question it sounds like he has a multiple entry tourist visa and he wants to leave and return for another 60-day stamp.
You can use the visa for three months from the visa issue date and you will get a 90-day entry stamp starting on the day of entry (which will be counted as day 1 of 90).
So unless there is a chance that you will have to delay your arrival until sometime in March there is no reason to delay getting the visa. Just plan it in for when it is most convenient for you.
Also remember that if you are using the online system and intend to submit your passport personally, rather than by post, there may not be any appointments left when you want them if you wait to book one.
However, when using the online system you can book your appointment well in advance if you want.
If you're not able (or willing) to buy insurance then...
You could try getting a single entry Non O for each half of your trip. However, they currently require £10,000 in the bank for 3 months before the application.
The METV James suggested is another option. Each entry gives you 60 days after which you would need to do a visa run or extend for 30 days at immigration.
They require £5,000 in the bank for six months before the application. They also require a letter from your employer but I have heard (but not verified) that they will accept pension letters as well.
Finally you could get a 60 day tourist visa on each side of your trip and extend it at immigration for 30 days or do a visa run and come back visa exempt.
I'm not sure if there are any other options for you.