You'll have to make a call on whether you can survive on the reduced BTWEA or not.
If you continue on it full-time, then you will not be able to apply for rent supplement at this stage. You will however be able to apply for medical card and will be granted one automatically provided that you would have qualified for one when you went on to the scheme. See here for medical card guidelines [broken link removed]
If you decide to leave the scheme, you'll get your Jobseekers reinstated without any difficulty, but you do have to be satisfying the genuinely seeking work criteria so if you don't wind the business down completely, you will have to satisfy them that you are only engaged in it part-time and that you continue to look for full-time work. Any income that you make from the business will be assessed euro for euro from your Jobseekers Allowance payment, but if you're not earning anything that shouldn't matter. YOu will have to prove this with figures though.
If you leave the scheme and return to Jobseekers payment, and if this is your only income, then you won't have difficulty getting medical card.
For rent supplement, you will likely need to be assessed by your local authority as in need of housing to receive it, unless you can show that you could afford the property from your own means when you first entered into the tenancy. Again, if you continue with the business, you will have to persuade rent supplement section that you are not involved in full-time work. There is an assessment process, but this is not likely to apply as any income that you get from self-employment will have already been taken off you through your Jobseekers Allowance claim. To be assessed by the council, just go in and fill out a form. The assessment must be completed before you can get rent supplement. If you could afford the tenancy from your own funds when you first entered into it, then you don't need to be assessed, and would simply apply to the rent supplement section for your local area. They won't pay it if you or any spouse/partner is working more than 30 hours a week.