Hi Clive,
I commute from the UK to my office in Rotterdam, and I use this toll tunnel most trips. Mainly because we have a cleint in Middelburg - and I may just pop-in and see them - I live in Brielle whilst in Holland - and the coast road from Middelburg to Brielle is way prettier than the inland motorway.
You can pay by UK credit card rather than Euro.
There are several major routes to the Tunnel from Belgium:
1. If you are driving on the A10 motorway, when you arrive at Brugge, take the Ring Road and follow the N9 then N49 to Zelzate and then Terneuzen.
2. A bit more cross country route - at Eeklo on the N49 head north on the N434, then N456 to IJzendijke - then take the N61 to Terneuzen. Shorter and prettier.
Look out for the camp grounds near Biervliet - they are located in the equivalent of a SSI - just really pretty.
3. If you are arriving at Zeebrugge - take the N376 then N61 "coast road".
Robert