The Wickes grouts I have used in the past have been quite poor really.
And the one product fits all category are worst of all (usually sticking like a grout, and grouting like an adhesive!)
Investing in a good quality powdered grout from Bal or Nicobond makes the job so much quicker and simpler. You can mix it relatively runny so that it is easy to float into all the gaps. Try not to entrain too much air in it when mixing. Cleans up nicely with a damp sponge after partially going off, and then a final rub over with a dry paper towel when all is fully dry.
If you want a really nice job, then treating the grout lines with lithofin grout protector works wonders as well.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.