I've done the UK to Holland direct crossing quite a number of times in a SEP, and I'm comfortable with the risk : but I must admit I think I'd probably advise the short channel crossing for the first trip - it's a fair old leg across to Holland, even direct from somewhere like Norfolk.
If you do the short crossing, you can still hop up the coast to Beligium or further if you wish - and whoever mentioned Ostend as an easy first destination is quite right.