I want to find out how I can discover the number of houses in any
given street in my home town of Coatbridge, North Lanarkshire.

nilrem,
For the most accurate answer to your question you need to speak to the
Housing & Property Services Department of the North Lanarkshire
Council. They maintain the definitive registry (including whether its
housing or commercial) of all properties in Coatbridge.

Contact details are:
Email: Coatbridgehousing@northlan.gov.uk
Phone: 01236 812561
Address:
Assistant Area Housing Manager
Housing & Property Services Department
North Lanarkshire Council
195 Main Street
Coatbridge ML5 3BW

However as a working alternative see here:
http://www.northlan.gov.uk/leisure+and+tourism/visitor+information/maps/location+maps+town+centres+visitors+info.html

Select Coatbridge Map,
Under ?Calculate Directions? type in given street name and Coatbridge,
Press ?Get Directions?.
Because a street number has not been entered a list of ?ambiguous
locations? maps will be displayed with corresponding street numbers in
brackets. Repeat as necessary.

Kind regards,
gfmaster