Lovely bike in original condition. Is the seatpost moving freely on this, that could make a difference to the value?
If you wanted to sell complete you will sell quicker/widen the appeal if postage is offered.
On here, complete and collected I’m going to stick my neck out and say around £100.
You could stick it on eBay for double that and wait for someone to come along but could be a long wait. There have been lots of Couriers sat on eBay for a long time at silly prices which was somewhat inflated during Covid.