The codes might seem daunting, but with familiarity, are really very straightforward.   Tafs and Metars follow similar codes.
Rather than repeat everything, look at this Martin Rowley website for good explanations.

On the weather page, links are given to several sources of Metars and Tafs

But Metars and Tafs are not specifically for Gliding
It is worth remembering that Tafs and Metars are prepared for general aviation and not specifically for gliding. 
Also note that CAVOK means (amongst other things) that there is no cloud below 5,000 feet.  So when there is 8/8ths cloud cover at 6,000 feet (eg approaching front), this is of no great consequence to an airliner, but is vital to a glider pilot.

Another limitation for gliding is that Tafs do not forecast the rising cloud base of cumulus during the morning. 
A Taf gives the lowest base expected during the period of the forecast.  By far the most accurate way to predict the final cumulus base is by using the dewpoint (which is unlikely to change much) and the forecast maximum temperature (Bradbury 400 ft / °C)

Also of note on the weather page is a link to look up metar history, eg for when you were flying 'yesterday'
 

If you are uncertain of the ICAO code for any particular UK airfield, then use the link ICAO < - > A/F name The World reports can be accessed by country and can be quite fascinating

EGGW 131031Z 131818 23012KT 9999 BKN020 TEMPO 0206 8000 -RA TEMPO 0618 3000 RADZ BKN004 PROB40 0818 22015G25KT=
 

repeating with colour to aid explanation EGGW131031Z13181823012KT9999BKN020TEMPO 0206 8000 -RATEMPO 0618 3000RADZ BKN004 PROB40 0818 22015G25KT= EGGW131031Z  131818  23012KT 9999 BKN020 TEMPO 0206 8000 -RA TEMPO 0618 3000 RADZ BKN004 PROB40 0818 22015G25KT = > > > > > > > > > > > Luton A/F with time of issue 13th at 1031Z period of forecast from 13th at 1800 Z to next day 1800Z forecast wind, 230°  at 12 knots visibility greater than 9999 metres, ie 10 kms + broken cloud (5-7/8s) at 2,000 feet above ground temporarily (ie, not all the time) between 02 and 06Z visibility 8,000 metres with light rain temporarily between 06 and 18Z (that means tomorrow) visibility 3,000 metres, rain & drizzle, broken cloud at 400 feet 40% probability between times 08Z and 18Z (tomorrow) wind from 220° 15 knots gusting 25 knots means end of report, ie nothing  accidentally omitted

It becomes automatic
With practice, decoding becomes almost automatic  It's a language that you read and your brain interprets without going through any conscious process.