Can I get free dial-up internet nowadays?

[#1]

I have a holiday home which, by its nature, is only used occasionally (family only - not rented out).
Currently I use a Vodafone PAYG mobile dongle to connect to the internet.
However having discovered that non-contract dial-up internet access use 0845 access numbers (Plusnet's for instance is 0845 1422000) and considering the fact I've got a BT phone service with "Evenings and Weekends" which nowadays includes 0845 numbers in the free allowance (without as far as I know any stipulation limiting which 0845 numbers are eligible), could I get dial-up internet at no charge during that period?
I realise it would be painfully slow but it would also be free - and potentially usable for forums and the like where there's not a lot of imagery content?

[#2]

Think you need to read BT charges. There are quite a few 0845 numbers that BT charge for and internet access is one of them.

http://www.productsandservices.bt.com/consumer/assets/downloads/BT_PhoneTariff_SpecialNos.pdf page 4

[#3]

Thanks - I was in the process of checking the (very) small print and unfortunately found this - http://www.productsandservices.bt.com/consumerProducts/displayTopic.do?topicId=32331#phone-plans :
0845 and 0870 numbers are also included within your inclusive call times (excluding indirect access numbers and dial-up internet access).
Pity, thought I was onto something there...
However the document you linked to notes the cost to an 0845 data link is only 0.51p/minute (at evenings and weekends) so it may be an alternative though the slow speed may mean that's not cheaper than the internet dongle...