I'm going through exactly the same thing, buying a house in the next month or so. I didn't get involved in the bonus so didn't need to worry about that, so just put exactly two thirds of all my players into the sell queues and were sold within 2 days. Saved making any tough decisions and essentially have exactly the same port, just a third of the size.
My port wasn't anywhere near as big as yours as only invested £1.5k about 2 years ago. Once my port hit £3k I completely derisked and removed my original investment. The £1.5k left was up to £3k when I did my recent sell so now have a port of £1k left but £2k in the bank. Wish I put a lot more in over the years and in hindsight shouldn't have derisked, but oh well, made some money for when I needed it!!
Good luck with the move!