Not clear on inc minutes and limits

[#1]

Currently on PN BB Prem Pro Opt 1 (although that no longer seems to be a listed BB product). 
Looking at home phone and have read all the FAQs etc but I can't suss this limits and credits issue.  Been with BT forever but no fan of their rip off charges or cust service so looking to change.  Average monthly bill with BT is around £25 including line rental etc and most calls are local E+W but some of those are made between 4pm and 6pm so how am I charged for those on home phone and does that mean I would need the anytime service instead?
I can see how the call costs are calculated for E+W (basically 4.5p setup for a call outside the restricted time) but can't see how this works within credit limits and the idea of having to monitor these and top these up before they run out is just too much hassle - as if I don't already have enough to do!
Anyone from PN care to explain this to me in simple terms - if it isn't simple then I don't want to know.
Also - I note that 'sometimes it may not be possible to keep your existing number'.  Under what circumstances is this the case and do I get to find out before I sign up?
Andy

[#2]

There is no call limit now on Homephone E&W or Anytime (normal geographical numbers).
With regards to the 4 pm to 6 pm calls you would need to calculate if these amount to more than £5 per month (the difference between  the two packages) because if you used the E&W package these would be charged for as they are outside of the 6 pm to 8 am and weekend limit.
Within the portal Phone Calls section there is a facility to add credit for the numbers that are not within your call plan - e.g. 0845/0870 and mobile numbers or for daytime calls if you are on E&W only. I usually click the drop-down list and add £5 for these as required. 

[#3]

Thanks
That helps but also sort of confirms my worst fears.  I don't want a PAYG home phone system that relies on vouchers for certain call types that are off plan. 
I pick it up, I make calls, I get billed , I pay the bill.  Anything more complicated than that I really can do without.
Complicated tariffs, credits, top-ups and vouchers are not for me - I have to put up with enough of that rubbish from the mobile operators.  Looks like I'll be sticking with BT for the foreseeable.
Thanks for responding.
Andy

[#4]

You'd only have to add credit if you spent over £50/month on calls on the £9.99 E+W package and £70/month on the Anytime+ package.  The credit limit is there as a means of protection so that you don't run up huge bills unexpectedly (BT & TalkTalk also give you a credit limit for calls).  It's NOT a PAYG phone service - you will get billed for calls and your credit will revert back to £50 or £70 the next month. 
With the size of phone bill you said you have you shouldn't need to bother about keeping an eye on things.
The two packages work in essentially the same way as the BT equivalents, i.e. E+W at £9.99 is essentially the same as BT together Option 2 and Anytime+ is the same as BT Together Option 3 (with the addition of 300 minutes of inclusive calls to the top 20 international destinations)

[#5]

Guys
Thanks for clarifying - I just couldn't get to the bottom of this top up business.  From what you describe it sounds much more manageable.  I'll have a think and possibly have a crack at the E+W package.
Cheers - appreciate all the advice
Andy

[#6]

Hi there,
As Paul says our Home Phone services are not PAYG only.
You have a credit limit, and all calls made are redeemed against this credit limit. If you exceed the credit limit for your product you  will need to top up to cover the rest of the months calls (you don't particularly need to watch this as you will receive emails when you are approaching your limit).
Alternatively, as Poppy says, you can top up by any amount during the month if you're expecting to make a lot of chargeable calls.