As I don’t really have the tools or the time to do it myself, will be taking to the garage to get it fixed. I will be asking for quotes, but just wondering what a guideline price is? Only one needs replacing 

You need to replace them as a pair, it is a VERY easy job, one hours labour would be what they should charge to do both, but it won't take that long.

+1  do the pair

Unless you had a newish set anyway and damaged one, the pair should be replaced as they will be out of balance otherwise! The previous posters were absolutely correct in pointing that out. I would suggest a cash transaction of around a hundred quid the pair perhaps more at a main dealer who will go through the books. Might be worth doing the springs too, if it is through wear and tear as they will be not much more then drop out, drop in.

Interesting when my S2 has a leaking rear shocker, Skoda who I leased the car from, chose to just replace one side. I’m pretty sure if I hadn’t had full maintenance contact the dealer would have insisted on me fitting both. I’ve always believed shockers and springs should be replaced as pairs 

Springs, shock absorbers, tyres, all are highly recommended to replace both sides (L and R) at the same time.

 

Only if you have a flat tyre shorly after replacing both, I would consider only 1 side, but in all cases, replace both. Wear and age can highly affect driving performance, so for safety it's highly recommended to change both.

Don't know if thats also a law, but I won't take the risk of having my car spinning left or right due to differences in suspension behaviour when I really need it. (eg when heavily braking)

 

12 hours ago, kevin defty said:

Interesting when my S2 has a leaking rear shocker, Skoda who I leased the car from, chose to just replace one side. I’m pretty sure if I hadn’t had full maintenance contact the dealer would have insisted on me fitting both. I’ve always believed shockers and springs should be replaced as pairs 

 

Yes, key term there was "leased" - never any need to do extra spending on a leased car!

Interestingly, the official erWin repair instructions for the rear suspension start thus:

1 - Shock absorber

❑ can be replaced separately

 

Make of that what you will.

was the next paragraph  "depending on who is paying"

Just had a quote from the garage £220 :( think I will be shopping around a bit!

36 minutes ago, Wench said:

Just had a quote from the garage £220 :( think I will be shopping around a bit!

 

If that's for both shocks supplied and fitted including VAT then it's probably about right.