Thank you for sending this to us to test :) We had the Bathroom cleaner.
I will answer your questions below but, to summarise, we found that this cleaner did not offer anything that a pack of antibacterial wipes (which we can buy for 50p a pack / 2 for £1 for 100 wipes) does not. We have two young children and we either do a thorough clean or we wipe up spills - there is no time for 'touch ups' like this which are pretty useless. I say 'useless' as this became apparent upon closer inspection of the packaging:
Here: To disinfect against bacteria... use enough product to thoroughly keep the surface wet for 5 minutes ... 5 minutes?! 
We concluded that this is all fur coat and no knickers :(
It looks pretty, smells pretty, appeals to people who have time on their hands to cosmetically 'touch up' between big cleans but ultimately does not provide a thorough clean and does not anti-bacterial those areas you have used it on for a quick wipe down (the whole point being that it is a 'quick' cleaner - 5 minutes soaking to disinfect; a quick cleaner does not equal!)
- How easy or difficult did you find the Mr Muscle Touch-Up Cleaner to use?
It is easy enough to use although the packaging says you can use toilet roll - this simply isn't up to the job even though we use a thick, branded type - we thought it should just state "a cleaning material such as a paper towel, cleaning cloth or sponge" as you put in your blurb. Also the dispenser squirted out more product than I expected and soaked through onto my fingers every time. I don't know how hand-friendly this cleaner is - (does the idea of 'touch up' suggest you don't need marigold's?!)
- How effective did you find Mr Muscle Touch-Up Cleaner?
It cleaned light grime well, struggled with anything tougher. It left the chrome streak-free but water splashes did not run off as they do when cleaning with other cleaners, so the effectiveness was short lived.
- Did you find that you used Mr Muscle Touch-Up Cleaner more regularly than your other cleaning products or not? If so, how often did you use Mr Muscle Touch-Up Cleaner?
We've used it a lot purely as it was a new toy 
the bathroom / kitchen sink have never been cleaned so often! I think as it has been designed to be easy on the eye (!) the bottle is out on the side and catches your eye more frequently.
- The RRP for the Mr Muscle Touch-Up Cleaner is £2.99, do you think you'll be likely to buy it again or not? If so, why? If not why not?
No, unless it was on offer and at least half that price - it is not value for money for us, especially compared to antibacterial wipes at 50p for 100.
- Mr Muscle Touch-Up cleaner is currently available for the kitchen and bathroom. Would you like Mr Muscle Touch-Up Cleaner for other areas of your house? If so, which areas?
A 100% antibacterial one (effective on contact) which could be used for highchairs, surfaces, tables etc. in the home would be interesting - much more useful in a busy household with young children.
- What did you like most about Mr Muscle Touch-Up Cleaner?
The smell! Although on reflection, that appears to come at the expense of effectiveness cleaning-wise.
- If it came up in conversation, would you recommend Mr Muscle Touch-Up Cleaner to your friends/family? If so why? If not, why not?
I would mention that I had tested it and, if they had the time and inclination and £3 to spare, I wouldn't deter them from buying it - though I would suggest the Kitchen one rather than the bathroom one (even though we didn't test the kitchen one) as the bathroom benefits more from a thorough clean rather than 'touch ups' in our opinion. Perhaps a downstairs loo which was used infrequently would be more appropriate for the 'bathroom' one.
Thank you again!