Nelliemoser, I have gone on about this on similar threads to what I think must be a boring extent, but if you investigate the Charities Aid Foundation (CAF), you might find it answers your needs. You set up an account and then make a regular payment of at least £10 per month into it. If you are eligible for Gift Aid, CAF claims it for you and pays it into your account, and they also take small contributions for their own expenses and for the NCVO. Then you can make online donations out of your account (including the Gift Aid that the charity could have claimed if you wish) or you can use the Charity Card they send you, and in both cases you can choose to give anonymously so that the charities can't get you. We have even sent an extra payment to the account at times so that we can give to a particular DEC appeal anonymously. You can also set up regular payments if you want, and I assume that they too can be anonymous.
The website is a bit slow, and not the most user-friendly one I have used, but it works and you can change which charities you give to without anyone complaining.
Hope that's of use to you.
Another silly little ABC game - shops we have loved and lost?
What is a reasonable minimum spend for an online grocery delivery??