My advice is to definitely do it.
The PPL merely lets you fly an aeroplane, the IMC will give you extra training and skills which in our cloudy climate could save your life and the lives of your passengers.
BUT... make sure you do it with a good school and don't accept a "sunshine rating". I was speaking to someone a few weeks ago who did an entire IMC course without an ADF in the trainer or any NDB tracking or holding practice.
Also I have heard of schools passing pupils without any ILS work, as this must be one of the most common landing aids I am amazed.
A good idea would be to find a school that offers the last 5 hours on a complex aircraft so that you learn about wobbly props and retracts at the same time reducing your total eventual expenditure.
Also this will make you a sharper and quicker instrument pilot owing to the faster decision speed required compared with a slow old C.150
When you have got a good rating you must practice to keep on top of the game, on some days I just go out and practice VOR let downs and various holds... sounds sad but I find it more challenging than aimlessly bimbling around.
Go for it is what I say.
B