Hiya Psims
Being realistic, 45 hours at 1 hour a weekend (assuming you book both days and loose 1 to weather) is going to take you almost a year. As 45 hours is a minimum requirement with most people requiring around 55 hours and the more limited availability of aircraft at the weekend (especially for the longer navigation and solo cross country flights), plus the probability of the whole weekend lost due to weather and getting good enough weather for your QXC and test - I'd suggest up to 2 years.
As foxmoth says trying to complete a few lessons in one day might speed things up but I doubt 3 lessons a day is wise given the learning work load. The school might not allow it or have the aircraft available to accommodate. Winter weather in the UK has been good for flying over the last 2 years with the worst months being at the start of the year.
One really good way to speed things up would be if your employer will allow you to take an extra day off each week as holiday over a protracted period - say 10-15 weeks? Week days are quieter so a better chance of the 2 lesson day. Taken with the weekend you could complete in a year.
Good luck!