The standard wooden (or now often plastic) pegs should be fine for a violin. The string tension required is fairly low and properly fitted pegs/holes with matched and round tapers.

Guitar strings require high tension, and mandolins even higher, because the strings must be at nearly breaking stress in order to provide reasonable sustain of the notes when plucked.

A violin has a continuous input from the bow so "sustain" is unnecessary, and lower string stress can be used - and is.

There are lots of "tricks" used for wobbly pegs, like putting rosin or chalk dust on them. The problem with all of these is that whatever you add gets embedded into the wood around the peg holes, making a proper repair much more difficult. Added "gunk" is also likely to increase the rate of wear, especially of the holes, so that a complete refinishing of pegs and holes will be needed sooner.

Wear on the pegs, unless you have an exceedingly fine instrument, is of relatively little consequence since pegs of modest quality are cheap enough to be tossed and replaced. (Very fine instruments may use pegs that are more expensive.)

Wear on the holes requires that they be "reamed" enough to make them round. Once numerous touch-up repairs have been done, the holes will be too large to ream again, and "inserts" or "inlays" must be installed so that there's enough wood there for fitting. A minor reaming may be a 10 minute job, while "putting wood back" may take several days. Luthiers often charge by the hour, and some count the time while the glue is setting.

If your pegs are "short" it's possible that they can't be seated sufficiently deeper just by pushing them into the hole a little firmer. All pegs are generally made a little "oversize" and it is intended that they be shaved-to-fit when installed. There also are true "oversize" pegs available if you have a "big hole" that's still sufficiently round.

If either the holes or the pegs have worn to the point where they're not "round" it will be difficult to make them hold securely with any amount of pressure or with any kind of added goop, gunk, slime, crud or "stuff" that you add to the problem. Any "additions," other than normal peg dope, will make proper repairs eventually more difficult - and probably more expensive.

Maintaining humidity is needed for wooden instruments to avoid cracking the larger "panels" of the instrument, and to avoid stressing glue joints so that they come apart. The amount of expansion/contraction that can occur at the peg/hole interface cannot be sufficient to exceed the "range of adjustment" available just by sliding the pegs in/out within the taper of the pegs and holes, unless the instrument is worn enough that the pegs are already at the end of their range of endwise travel.

Although extremes of humidity can be damaging to wooden instruments, the moisture absorbed within the wood must change before the stresses on the wood can change. It normally takes several days of exposure to a change in humidity for the moisture contained inside the wood is significantly affected. Many luthiers "age" their wood for years before accepting that the moisture level is sufficiently stable to start work on a piece.

Brief exposures of the duration necessary to take your instrument to the pub for a session will not significantly affect the moisture level inside the wood, unless you plan to dip it in your ale, if the instrument is returned to the stable humidity conditions back at the house within a few hours. The amount by which the absorbed moisture in the fiddle can change the peg/hole fit in that time will be "invisible" in any effect on your playing.

Sudden temperature changes can be more rapidly harmful, so a case (or a large rag) to enclose the instrument in-transit, and reasonable time for the instrument to "come to temperature" before tuning up, are a good idea when leaving the house.

Talk to a fiddle luthier, and you'll likely find that the fiddle can be made much better behaved at fairly minimal cost. Finding a reasonably competent shop may be more expensive (time, effort, and tranport) than the actual repair.

John