Would you really go through POL?
I always tried to route away from there if possible. You would also be going against the North South flow of traffic. Usually the south bound would be NGL DCS Lakey,Man etc But at FL90 you would be a right pain in the bum so better to go outside and then come back in again to get round the outside of the Man arrivals. And North POL, TLA
Personally I would Route to NGY then pick up a service from Warton outside. Then rejoin and head down the east of wales on those airways running down towards Cardiff. Then once down south and past london then cut across.
As soon as you go near POL or HON you will get in everyones way and more than likely get vector'd all over the place that is you don't get a slot.
Also that way if you need to escape you have PIK, Blackpool, Liverpool, Man,BHX, Cardiff, Filton, Exeter.
And I wouldn't have a problem doing it.