want to start an isa

advice
there

google.

Is ISA an acronym for important spelling advice ?

Stick it under the mattress where you can see it.

Go for a stocks & shares ISA. I'd suggest you buy some exchange traded funds.
Alliance trust savings allows good flexibility in choice of investments. You can invest in ETFs (lowest charges), managed funds (higher charges, with alleged experts running them) or individual shares.
I'd split the investment into 3-4 different things. As the markets may not perform that great going forward, I'd suggest including some shares that pay a healthy dividend. The iShares FTSE UK Dividend Plus (IUKD) might be worth including.
A stocks & shares ISA should normally return more than a cash ISA, though of course that will not always be the case.
http://www.alliancetrust.co.uk/alliancetrustsavings/isa.htm

"--- though of course that will not always be the case ".
A bit of an understatement I would have thought.

my one has returned ca 45% this year. How many years is that at the current interest rate for a cash ISA?

How much did it lose the year before out of curiosity ?
In other words are you back to where you were a few years ago yet ?

Btw aren't you the one who is complaining that UK is the rip -off kingdom of the world.
Seems that you are benefiting somewat in some form or manner.

I sold a fair bit last year & bought pharma, but did certainly lose money. The 45% is actually after 2 years. One of my funds went up ca 90% this year. (Invesco Perpetual Latin American Acc)
The rip off Britain was a cut & paste job to give the fred a bit of balance. I don't think things are very well run over here.

So you're up 45 % from your level 2 years ago.
If true, congratulations.
Not very representative of how most, if not all, others have done.

The FTSE100 is flat after 2 years, so many will have not made nor lost money.

Exactly.
You seem to be arguing against yourself here.

If you had your money in quality companies, you'd still have got dividends and probably not done any worse than a cash iSA

Yes, but you would have got the same dividends, if you held the same charges outside an ISA, but you wouldn't have to pay management charges.

For ordinary rate taxpayers shares ISA's make NO SENSE. OK they are free of capital gains tax, but you are allowed £10,800 for that anyway. And, there is no tax relief on the dividends (different for higher rate taxpayers), so why hold shares in an ISA ?

And of course, at the end of the day shares whether in an ISA or not are subject to Inheritance Tax (if estate over £340k).

for 'charges' read 'shares'