i found the best thing to do was to get a credit card with my bank and set up online banking. Then i mostly spent on my credit card and ever few weeks just transferred the money over i had left in my english account. Every now and then when i needed cash i would withdraw on my switch... which you can do but charges you each time - so i tried to do this as little as possible.
Debit/ATM cards linked to my accounts back home, with a decent yet not excessive amount of cash on hand has become my preffered way of carrying funds... I have all but given up on Travellers Checks in recent years... I think because of problems with theft Retailers have found themselves accepting stolen checks and not being payed by their distributor because they were stolen... I would guess this leaves a bad taste in a retailers mouth the next time someone tries to use a travellers check... Just a guess, but I'd guess thats the root of the problem with them.