I've successfully used 1.5 inch PVC pipe. Here in the US, we get 1inchx2inch lumber, 8 feet long. Cut 12 inch sections. Place the section inside the PVC ( it fits snuggly), and use drywall screws to make a joint. For curves where two pieces of pipe meet use clear silicone tubing instead of the lumber. There's a specific diameter that also fit's snuggly inside the pipe. I made home made sandbags to place on the pipe to keep it from moving. Take a ziplock freezer bag, fill with peagravel and zip the bag closed. Place that bag inside of a 30 inch x 30 inch piece of rip stop painters tarp. Fold the tarp over the ziplock bag and tape it up with duct tape.
If you like this kind of track you can make a jig to bend PVC to make curved fittings. To use the jig you cut your pipe to say 20 inches, place caps on either end to make it airtight and heat the pipe up and bend it in the jig to any angle you need. The capped ends keep the pipe from crinkling when bent.
There's a few photos here:
http://strictlyrc.net/
Not sure what your budget is but for lap timing we use Alycat race timing software:
http://www.alycat.com
Alycat is an Aussie company. You can use the software and not use a timing hardware system but you'd need someone to push keys ona computer as cars go by.
And we use I-LapRC race timing hardware:
http://www.rclapcounter.com
Sounds like you'll be racing on bare concrete. If so I'd suggest vacuuming and giving your race area a damp mop to get rid of any dust on the surface before racing.
Have fun!!!