Today with the BROADBAND “ADSL” solution, you can surf and email at the same time as using the telephone. Cable is another popular option. The cost of such services start at £15 per month but can be considerably more. For this you get by default the use as much as you like option with a faster link that makes the Internet and large emails much more attractive and less time consuming.
Unfortunately some people live or work too far away from their local telephone exchange to get the high speed (80 Mb/s) ADSL service.
If your business already has a connection to a cable company, there are other fast options available.
A high speed line does not solve all the problems - some Internet sites are often busy and hence slow. Sometimes the Internet becomes congested by storms of junk or virus generated email. Some ISPs become congested as the kids arrive home from school or at weekends.
Wireless Internet (WiFi) connection is now easy and reasonably secure. In some buildings, WiFi signals are absorbed by metal e.g.insulated plasterboard, so a cabled solution may be better.
I rely on understanding your needs before spending your cash.