Ours down in Suffolk do the Lepto 4 only, yearly and the other one 3 yearly, altho we pay the same yearly. It has deffo changed since I first had dogs.
Our vets like you to have the boosters on time for the first year (assuming we are talking pups) but the second and subsequent years they give 3 month's grace b4 having to have whole new course. (I did not know this until I had a reason for not going on the anniversary of the date at one time). But doing this could be a bit tricky if it comes to needing to put the dogs in kennels for any reason during the 3 month grace period.