Hi Imran, you will be competing with established plasterers who have all the experience they need. You will not only have to be good at what you are doing but be able to turn out the quantity as well as quality.
So when pricing for jobs @ £130 a day is irrelevant, as if it takes you 2 days to do a days plastering you will not get the job, simple as that. So quality will show with your customer feedback and recommendations but you will have to start to be competitive and take it from there. If you have not acquired the speed yet then you may find you will be earning a lot less than your competitors.
Also consider if you are not going to declare then you may be traced by payment by cheque. To get cash on every job usually means a discount!
You are starting at the right time of year but it could take a year or two to get an established name.
Good luck with it and don't start with the racist crap on here your blood is red like anyone else's.