Q.fig tree – yellow leaves
We have purchased from B&Q shop about 6 weeks ago a fig to put it in our back garden. It was a nice healthy tree. About a week ago leaves started to turn yellow. Summer here in Scotland is very cold this year with lots of rain. We are not sure what to do. Should we leave tree outside or take inside or is there anything else we could do? Many thanks.

Are you planning to keep the fig in a container, or plant it in the ground? Hopefully, if you're going to put it in the ground, you got a cold weather variety. With the proper care, you can do either. These articles should answer your questions, and give you some ideas: https://www.gardeningknowhow.com/edible/fruits/figs/fig-with-yellow-leaves.htm
https://www.gardeningknowhow.com/edible/fruits/figs/how-to-grow-figs.htm
https://www.gardeningknowhow.com/edible/fruits/figs/fig-cold-protection.htm
What to do now may still be a problem. It may be getting too late in the year to plant in the ground, if you were wanting to. Continue care as best you can, make sure your tree has plenty of water and the soil is draining well, and protect it when winter comes (it will drop its leaves.) Next spring, proceed with good maintenance.
You might want to access the good advice available to you from the Master Gardener Program. This link will help you locate the nearest organization: http://mastergardeners.org.uk/get-involved/find-your-nearest-master-gardener/