The sooner you start to save, the more manageable the cost will be.
Decide where to stash your savings. Maybe you already have an online bank account that lets you set up a separate pot for the wedding.
Otherwise, open a straightforward instant access savings account.
If you have a large and unexpected expense getting in the way of your saving plan, there are some credit cards that can give 0% interest on purchases for up to a year, or even longer.
Some people use these cards to spread that cost over a long period of time, which can then allow them to continue putting money into their savings each month.
These credit card offers do expire, with the APR reverting to a much higher rate.
So, make sure to set up a Direct Debit to fully pay off the balance within the 0% period.