I would go for "cystemsolutions.co.uk" but a good idea would be to buy the domain name "systemsolutions.co.uk" and then redirect to your site so that you won't be losing any business. But I have a feeling that systemsolutions.co.uk is already taken.
I took your advice and found that systemsolutions.co.uk was taken so I then spent a bit of time thinking about the name of our business and also the name in general and came to the decision that a name change was needed so that's exactly what's happening.
I decided to go for Dot Media Solutions.co.uk. I like it and sounds a lot more interesting than Cystem Solutions etc.