It all sounds as if it is likely to happen now Mw.
Forget the cleaning upstairs at present, and concentrate on looking for somewhere that you wish to purchase. If you can get somewhere with vacant possession, then - indeed - you could be in by February next year.
I would very much recommend that you consider having whatever removal company you use also to do your packing. Although, obviously, there are some things you may wish to pack yourself (I did with my large display cabinet of fragile gymnastic statues and memoralibilia), it does mean that right up to 48 before the move you can live comfortably in reasonably normal circumstances. They usually pack one day and move you the next. If you are not moving too far away, they will leave the bed and such things as your fridge and add those on the morning of the actual move.
You really must now start concentrating on (A) completing that sellers pack from your solicitor. Once you start and go through it page by page, it is far less daunting than looking at it as it is. Also (B) you really must start looking for somewhere to purchase - you now know how much you can spend.
Do not forget that whatever you do get as purchase price, you need to take out your EA fees, solicitor fees, and Land Registry for your purchase, and removal fees. Also do allow money for spending on your new place - as has been said, new properties tend to eat up money in the first year.
Mw - this is the exciting part - looking for and preparing for you new ever-home. Involve your children -yes, but remember it will be YOU who will be living there.