Yes, but legally you need OFCOM to issue you a Variation of Ship's Licence, and its use is prohibited within 30 miles(?) of UK high water line. The dealer should refuse to add the channel without the VoL.
Some models can access Ch31 just by choosing the relevant channel set. You may lose the use of M1/M2 but 12 miles out you probably won't mind. You can of course change back during your return.
Most Dutch marinas, if not all, can be entered without prior contact and have a jetty available for getting of for announcing yourself, either by intercom or a walk to the office.
Some even have someone meeting you at the busier moments that will give you directions on where to moor.
There are also marinas where an available berth is marked with a green sign and the unavailable ones have a red sign.
I can not remember the last time I used channel 31. (Me and my boat live in Holland)
+1. We had our new VHF set supplied with Ch 31 as we live in the Netherlands, and we’ve not used Ch 31 in 3 years. Mobile phone or visitors waiting pontoon........