I'm based at EGNS with my Bulldog (single-engne-piston). I've flown all the routes you mention, many times. In my opinion, always best to minimize the water-crossing. That suggests coasting-out from Whitehaven to enter IOM zone at Laxey, then tracking down the East Coast of IOM to EGNS. It makes your trip from Tatenhill slightly longer -- but not much longer. Just go up the low-level corridor to Blackpool, then up the West coast to Whitehaven for the crossing. It makes your crossing 15 miles rather than 60....
Also, at risk of stating the obvious, be very careful with wx planning. IOM can get bad, quickly, this time of year especially. With your IMC you can get radar vectors to the ILS at Ronaldsway (class D), but you really don't want to be doing that in true IMC in a little cessna.
Enjoy.