Resort towns in the Italian Lakes are well-served by trains from Milan, which is a two-hour flight from the UK (to either Malpensa or Orio al Serio International) by regular and budget airlines.
For Lake Garda, it’s best to fly direct to Verona (Brescia) Airport, also served by both standard and low-cost airlines from the UK, some of them seasonal. From the airport, the lake resorts are easily accessible by hire car, bus or rail. Car and passenger ferries on the lake itself will help you negotiate Garda once you get there.
For train travel from the UK to the Italian Lakes, see seat61.com. By car, count on around 12 hours' straight driving time to get from the Channel ferry and Eurotunnel port of Calais to Sirmione on Lake Garda.