I agree with what's already been said. My two are no longer vaccinated but are titre tested instead. As an example, my 8 year old Cocker had the normal puppy vaccinations and a booster one year later. At ages 4 and 7 he was titre tested to check immunity against parvovirus, distemper and hepatitis (those are the three diseases covered by the core vaccinations given to dogs in the UK). He still had immunity and didn't need a booster, let alone re-starting the lot from scratch. I will have him titre tested again when he's 10.
The vaccination that there isn't a titre test for is the one for Leptospirosis. Most vets recommend that it's given annually because it only lasts for 12 months at the most. I don't have my two vaccinated against Leptospirosis at all. The vaccine only covers a few of many strains and anecdotally is more likely to cause a reaction than the parvo, distemper and hepatitis vaccination. Leptospirosis is a nasty disease, but is very treatable if recognised early enough.
If you decide to go for titre testing you'll probably find that your vet doesn't do it in house and will want to charge you around £100 to take bloods and send them to a lab. for testing. Try phoning other vets on the Island to see if any offer in house testing using the Vaccicheck kit. An increasing number of vets do, and will probably charge around £40.
I'm in the New Forest and my vet at Lyndhurst does in house titre testing, so that might be worth considering if you can't find one on the IOW.