Hi there.
Firstly welcome to the forum and well done for deciding to fulfil your ambition of gaining a PPL. I can tell you now it's a very rewarding experience indeed, but one that comes with many challenges, and lots of emotional ups and downs.
Obviously whatever you decide to do will be wholly down to your decision at the end of the day, and we can only give our opinion which for most will be based on our own personal experiences.
The first thing you will need to bare in mind with doing 1 lesson per month is of course the overall time over which you will train. Based on 45 hours minimum you would of course need 45 months which is nearly 4 years. However, do bare in mind that those who do training spread out over such a time frame usually require much more than 45 hours as there will be a continual process of refreshing yourself on what you previously learned in the last lesson, and the basic controls and fundamentals of flying will take much longer to master. With this in mind you should consider that it is likley to take you 60 hours+ of training to achieve your PPL, and maybe even more. This now puts you into the 5 years camp, and I suspect that during this period you are likley to experience low periods and there is always a risk that the very slow progression may eventually cause you to give up on the training and cut your losses, leaving you out of pocket and with no PPL license to boot.
With this first point in mind I would personally say that where possible you need to try and get blocks of training done to ensure your progression is steady and visible. Otherwise your morale will be a constant battle.
The next consideration with learning to fly in this country is that the weather will constantly mean cancelled lessons, and even more so as you are in not so sunny Scotland. This will further extend the training period, so in summary I would say that basing your training on 1 lesson per month would not be a sensible approach.
You could perhaps ensure that you have at least 1 lesson per month but should aim to get up to 3 or 4 if you can, and should time and money allow it even more. Block training, in my experience is much more advantageous as it means you do not have to waste time each lesson refreshing yourself on the basics.
Lets say you have £3000 saved up already, I would try and spend this on lessons as quickly as possible as this will mean you will get a good chunk of the training done as this will give you a good grounding of basic controls and flight knowledge right off the bat. You can then resort to 1, 2 or 3 lessons per month there after to finish the training and you will also have ample time to do the theory at this stage to. You will also significantly reduce the overall time that your training takes so all in all I believe this to be a much safer approach.
Anyhow, this is of course my opinion but I hope it helps. Others might suggest otherwise however.
Good luck with your flying, fly safe and enjoy the ride. I can assure you it's a very interesting and challenging one.
