My recommendation is to find a friend/mentor with experience and ask him along for the first few flights. It is certainly doable. You need to give yourself a few days leeway, the weather doesn't always fully cooperate, even in summertime. I have flown to Stockholm Bromma, Linkoping Saab and a few other fields in Sweden several times in singles and twins over the years starting from Belgium.
The last flight to ESSL was 4:24 at economy cruise in BE36.
My suggested VFR routing would be London area via DVR, KOK, along the Belgian, Dutch, German coast to Denmark then cross to Sweden. Under VFR you would be restricted in altitude along the Dutch coast due to class A airspace.
Get yourself the full Skydemon and start planning.